Flexible flow control mechanism for NG-RAN interfaces

ABSTRACT

An apparatus of a RAN node in which flexible feedback for user data transferred between RAN nodes is described. The DL PDCP PDUs to be delivered to a UE is transmitted over an Xn or X2 interface between RAN and NG-RAN nodes, respectively. Feedback received allows transmitting RAN node to control downlink user data flow. The feedback contains a DDDS frame that includes a highest transmitted and delivered PDCP SN indicator parameter that respectively indicates whether a highest transmitted and successfully delivered PDCP PDU is present in the DDDS message and a highest transmitted and successfully delivered PDCP SN PDU parameter that provides feedback respectively about a transmitted status of the PDU sequence and an in-sequence delivery status of the PDUs to the UE. Buffered PDUs reported by the DDDS message are removed from memory as transmitted or successfully delivered PDUs.

PRIORITY CLAIM

This application claims the benefit of priority under 35 U.S.C. 119(e)to U.S. Provisional Patent Application Ser. No. 62/586,764, filed Nov.15, 2017, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments pertain to radio access networks (RANs). Some embodimentsrelate to cellular and wireless local area network (WLAN) networks,including Third Generation Partnership Project Long Term Evolution (3GPPLTE) networks and LTE advanced (LTE-A) networks as well as legacynetworks, 4^(th) generation (4G) networks and 5^(th) generation (5G) NewRadio (NR) (or next generation (NG)) networks. Some embodiments relateto flow control between NR nodeBs (gNBs).

BACKGROUND

The use of various types of systems has increased due to both anincrease in the types of devices user equipment (UEs) using networkresources as well as the amount of data and bandwidth being used byvarious applications, such as video streaming, operating on these UEs.To increase the ability of the network to contend with the explosion innetwork use and variation, the next generation of communication systemsis being created. As per the norm, with the advent of any newtechnology, the introduction of a complex new communication systemengenders a large number of issues to be addressed both in the systemitself and in compatibility with previous systems and devices. Suchissues arise, for example, from the multitude of interfaces that may beused when NG systems and devices are used in conjunction with earliernetworks and devices.

BRIEF DESCRIPTION OF THE FIGURES

In the figures, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The figures illustrate generally, by way of example, but notby way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 illustrates a UE in accordance with some embodiments.

FIG. 2 illustrates a base station or infrastructure equipment radio headin accordance with some embodiments.

FIG. 3 illustrates millimeter wave communication circuitry in accordancewith some embodiments.

FIG. 4 is an illustration of protocol functions in accordance with someembodiments.

FIG. 5 is an illustration of protocol entities in accordance with someembodiments.

FIG. 6 illustrates an architecture of a system of a network inaccordance with some embodiments.

FIG. 7 illustrates a combined 4G and NG communication system inaccordance with some embodiments.

FIG. 8 illustrates interconnections for gNBs in accordance with someembodiments.

FIG. 9 illustrates information flow between nodes in accordance withsome embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

Any of the radio links described herein may operate according to any oneor more of the following exemplary radio communication technologiesand/or standards including, but not limited to: a Global System forMobile Communications (GSM) radio communication technology, a GeneralPacket Radio Service (GPRS) radio communication technology, an EnhancedData Rates for GSM Evolution (EDGE) radio communication technology,and/or a Third Generation Partnership Project (3GPP) radio communicationtechnology, for example Universal Mobile Telecommunications System(UMTS), Freedom of Multimedia Access (FOMA), 3GPP Long Term Evolution(LTE), 3GPP Long Term Evolution Advanced (LTE Advanced), Code divisionmultiple access 2000 (CDMA2000), Cellular Digital Packet Data (CDPD),Mobitex, Third Generation (3G), Circuit Switched Data (CSD), High-SpeedCircuit-Switched Data (HSCSD), Universal Mobile TelecommunicationsSystem (Third Generation) (UMTS (3G)), Wideband Code Division MultipleAccess (Universal Mobile Telecommunications System) (W-CDMA (UMTS)),High Speed Packet Access (HSPA), High-Speed Downlink Packet Access(HSDPA), High-Speed Uplink Packet Access (HSUPA), High Speed PacketAccess Plus (HSPA+), Universal Mobile TelecommunicationsSystem-Time-Division Duplex (UMTS-TDD), Time Division-Code DivisionMultiple Access (TD-CDMA), Time Division-Synchronous Code DivisionMultiple Access (TD-CDMA), 3rd Generation Partnership Project Release 8(Pre-4th Generation) (3GPP Rel. 8 (Pre-4G)), 3GPP Rel. 9 (3rd GenerationPartnership Project Release 9), 3GPP Rel. 10 (3rd Generation PartnershipProject Release 10), 3GPP Rel. 11 (3rd Generation Partnership ProjectRelease 11), 3GPP Rel. 12 (3rd Generation Partnership Project Release12), 3GPP Rel. 13 (3rd Generation Partnership Project Release 13), 3GPPRel. 14 (3rd Generation Partnership Project Release 14), 3GPP Rel. 15(3rd Generation Partnership Project Release 15), 3GPP Rel. 16 (3rdGeneration Partnership Project Release 16), 3GPP Rel. 17 (3rd GenerationPartnership Project Release 17), 3GPP Rel. 18 (3rd GenerationPartnership Project Release 18), 3GPP NG, 3GPP LTE Extra, LTE-AdvancedPro, LTE Licensed-Assisted Access (LAA), MulteFire, UMTS TerrestrialRadio Access (UTRA), Evolved UMTS Terrestrial Radio Access (E-UTRA),Long Term Evolution Advanced (4th Generation) (LTE Advanced (4G)),cdmaOne (2G), Code division multiple access 2000 (Third generation)(CDMA2000 (3G)), Evolution-Data Optimized or Evolution-Data Only(EV-DO), Advanced Mobile Phone System (1st Generation) (AMPS (1G)),Total Access Communication System/Extended Total Access CommunicationSystem (TACS/ETACS), Digital AMPS (2nd Generation) (D-AMPS (2G)),Push-to-talk (PTT), Mobile Telephone System (MTS), Improved MobileTelephone System (IMTS), Advanced Mobile Telephone System (AMTS), OLT(Norwegian for Offentlig Landmobil Telefoni, Public Land MobileTelephony), MTD (Swedish abbreviation for Mobiltelefonisystem D, orMobile telephony system D), Public Automated Land Mobile (Autotel/PALM),ARP (Finnish for Autoradiopuhelin, “car radio phone”), NMT (NordicMobile Telephony), High capacity version of NTT (Nippon Telegraph andTelephone) (Hicap), Cellular Digital Packet Data (CDPD), Mobitex,DataTAC, Integrated Digital Enhanced Network (iDEN), Personal DigitalCellular (PDC), Circuit Switched Data (CSD), Personal Handy-phone System(PHS), Wideband Integrated Digital Enhanced Network (WiDEN), iBurst,Unlicensed Mobile Access (UMA), also referred to as also referred to as3GPP Generic Access Network, or GAN standard), Zigbee, Bluetooth®,Wireless Gigabit Alliance (WiGig) standard, mmWave standards in general(wireless systems operating at 10-300 GHz and above such as WiGig, IEEE802.11ad, IEEE 802.11ay, and the like), technologies operating above 300GHz and THz bands, (3GPP/LTE based or IEEE 802.11p and other),Vehicle-to-Vehicle (V2V), Vehicle-to-X (V2X), Vehicle-to-Infrastructure(V2I), and Infrastructure-to-Vehicle (I2V) communication technologies,3GPP cellular V2X, DSRC (Dedicated Short Range Communications)communication systems such as Intelligent-Transport-Systems and others.

Aspects described herein can be used in the context of any spectrummanagement scheme including, for example, dedicated licensed spectrum,unlicensed spectrum, (licensed) shared spectrum (such as Licensed SharedAccess (LSA) in 2.3-2.4 GHz, 3.4-3.6 GHz, 3.6-3.8 GHz and furtherfrequencies and Spectrum Access System (SAS) in 3.55-3.7 GHz and furtherfrequencies). Applicable exemplary spectrum bands include IMT(International Mobile Telecommunications) spectrum (including 450-470MHz, 790-960 MHz, 1710-2025 MHz, 2110-2200 MHz, 2300-2400 MHz, 2500-2690MHz, 698-790 MHz, 610-790 MHz, 3400-3600 MHz, to name a few),IMT-advanced spectrum, IMT-2020 spectrum (expected to include 3600-3800MHz, 3.5 GHz bands, 700 MHz bands, bands within the 24.25-86 GHz range,for example), spectrum made available under the Federal CommunicationsCommission's “Spectrum Frontier” NG initiative (including 27.5-28.35GHz, 29.1-29.25 GHz, 31-31.3 GHz, 37-38.6 GHz, 38.6-40 GHz, 42-42.5 GHz,57-64 GHz, 71-76 GHz, 81-86 GHz and 92-94 GHz, etc), the ITS(Intelligent Transport Systems) band of 5.9 GHz (typically 5.85-5.925GHz) and 63-64 GHz, bands currently allocated to WiGig such as WiGigBand 1 (57.24-59.40 GHz), WiGig Band 2 (59.40-61.56 GHz), WiGig Band 3(61.56-63.72 GHz), and WiGig Band 4 (63.72-65.88 GHz); the 70.2 GHz-71GHz band; any band between 65.88 GHz and 71 GHz; bands currentlyallocated to automotive radar applications such as 76-81 GHz; and futurebands including 94-300 GHz and above. Furthermore, the scheme can beused on a secondary basis on bands such as the TV White Space bands(typically below 790 MHz) where in particular the 400 MHz and 700 MHzbands can be employed. Besides cellular applications, specificapplications for vertical markets may be addressed, such as PMSE(Program Making and Special Events), medical, health, surgery,automotive, low-latency, drones, and the like.

Aspects described herein can also be applied to different Single Carrieror OFDM flavors (CP-OFDM, SC-FDMA, SC-OFDM, filter bank-basedmulticarrier (FBMC), OFDMA, etc.) and in particular 3GPP by allocatingthe OFDM carrier data bit vectors to the corresponding symbol resources.

FIG. 1 illustrates a UE in accordance with some embodiments. The userdevice 100 may be a mobile device in some aspects and includes anapplication processor 105, baseband processor 110 (also referred to as abaseband sub-system), radio front end module (RFEM) 115, memory 120,connectivity sub-system 125, near field communication (NFC) controller130, audio driver 135, camera driver 140, touch screen 145, displaydriver 150, sensors 155, removable memory 160, power managementintegrated circuit (PMIC) 165 and smart battery 170.

In some aspects, application processor 105 may include, for example, oneor more CPU cores and one or more of cache memory, low drop-out voltageregulators (LDOs), interrupt controllers, serial interfaces such asserial peripheral interface (SPI), inter-integrated circuit (I²C) oruniversal programmable serial interface circuit, real time clock (RTC),timer-counters including interval and watchdog timers, general purposeinput-output (IO), memory card controllers such as securedigital/multi-media card (SD/MMC) or similar, universal serial bus (USB)interfaces, mobile industry processor interface (MIPI) interfaces andJoint Test Access Group (JTAG) test access ports.

In some aspects, baseband processor 110 may be implemented, for example,as a solder-down substrate including one or more integrated circuits, asingle packaged integrated circuit soldered to a main circuit board,and/or a multi-chip module containing two or more integrated circuits.

FIG. 2 illustrates a base station in accordance with some embodiments.The base station radio head 200 may include one or more of applicationprocessor 205, baseband processor 210, one or more radio front endmodules 215, memory 220, power management circuitry 225, power teecircuitry 230, network controller 235, network interface connector 240,satellite navigation receiver 245, and user interface 250.

In some aspects, application processor 205 may include one or more CPUcores and one or more of cache memory, low drop-out voltage regulators(LDOs), interrupt controllers, serial interfaces such as SPI, I²C oruniversal programmable serial interface, real time clock (RTC),timer-counters including interval and watchdog timers, general purposeIO, memory card controllers such as SD/MMC or similar, USB interfaces,MIPI interfaces and Joint Test Access Group (JTAG) test access ports.

In some aspects, baseband processor 210 may be implemented, for example,as a solder-down substrate including one or more integrated circuits, asingle packaged integrated circuit soldered to a main circuit board or amulti-chip module containing two or more integrated circuits.

In some aspects, memory 220 may include one or more of volatile memoryincluding dynamic random access memory (DRAM) and/or synchronous dynamicrandom access memory (SDRAM), and nonvolatile memory (NVM) includinghigh-speed electrically erasable memory (commonly referred to as Flashmemory), phase change random access memory (PRAM), magnetoresistiverandom access memory (MRAM) and/or a three-dimensional crosspointmemory. Memory 220 may be implemented as one or more of solder downpackaged integrated circuits, socketed memory modules and plug-in memorycards.

In some aspects, power management integrated circuitry 225 may includeone or more of voltage regulators, surge protectors, power alarmdetection circuitry and one or more backup power sources such as abattery or capacitor. Power alarm detection circuitry may detect one ormore of brown out (under-voltage) and surge (over-voltage) conditions.

In some aspects, power tee circuitry 230 may provide for electricalpower drawn from a network cable to provide both power supply and dataconnectivity to the base station radio head 200 using a single cable.

In some aspects, network controller 235 may provide connectivity to anetwork using a standard network interface protocol such as Ethernet.Network connectivity may be provided using a physical connection whichis one of electrical (commonly referred to as copper interconnect),optical or wireless.

In some aspects, satellite navigation receiver 245 may include circuitryto receive and decode signals transmitted by one or more navigationsatellite constellations such as the global positioning system (GPS),Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS), Galileoand/or BeiDou. The receiver 245 may provide data to applicationprocessor 205 which may include one or more of position data or timedata. Application processor 205 may use time data to synchronizeoperations with other radio base stations.

In some aspects, user interface 250 may include one or more of physicalor virtual buttons, such as a reset button, one or more indicators suchas light emitting diodes (LEDs) and a display screen.

A radio front end module may incorporate a millimeter wave radio frontend module (RFEM) and one or more sub-millimeter wave radio frequencyintegrated circuits (RFIC). In this aspect, the one or moresub-millimeter wave RFICs may be physically separated from a millimeterwave RFEM. The RFICs may include connection to one or more antennas. TheRFEM may be connected to multiple antennas. Alternatively bothmillimeter wave and sub-millimeter wave radio functions may beimplemented in the same physical radio front end module. Thus, the RFEMmay incorporate both millimeter wave antennas and sub-millimeter waveantennas.

FIG. 3 illustrates millimeter wave communication circuitry in accordancewith some embodiments. Circuitry 300 is alternatively grouped accordingto functions. Components as shown in 300 are shown here for illustrativepurposes and may include other components not shown here.

Millimeter wave communication circuitry 300 may include protocolprocessing circuitry 305, which may implement one or more of mediumaccess control (MAC), radio link control (RLC), packet data convergenceprotocol (PDCP), radio resource control (RRC) and non-access stratum(NAS) functions. Protocol processing circuitry 305 may include one ormore processing cores (not shown) to execute instructions and one ormore memory structures (not shown) to store program and datainformation.

Millimeter wave communication circuitry 300 may further include digitalbaseband circuitry 310, which may implement physical layer (PHY)functions including one or more of hybrid automatic repeat request(HARQ) functions, scrambling and/or descrambling, coding and/ordecoding, layer mapping and/or de-mapping, modulation symbol mapping,received symbol and/or bit metric determination, multi-antenna portpre-coding and/or decoding which may include one or more of space-time,space-frequency or spatial coding, reference signal generation and/ordetection, preamble sequence generation and/or decoding, synchronizationsequence generation and/or detection, control channel signal blinddecoding, and other related functions.

Millimeter wave communication circuitry 300 may further include transmitcircuitry 315, receive circuitry 320 and/or antenna array circuitry 330.

Millimeter wave communication circuitry 300 may further include radiofrequency (RF) circuitry 325. In an aspect, RF circuitry 325 may includemultiple parallel RF chains for one or more of transmit or receivefunctions, each connected to one or more antennas of the antenna array330.

In an aspect of the disclosure, protocol processing circuitry 305 mayinclude one or more instances of control circuitry (not shown) toprovide control functions for one or more of digital baseband circuitry310, transmit circuitry 315, receive circuitry 320, and/or radiofrequency circuitry 325.

The transmit circuitry of may include one or more of digital to analogconverters (DACs), analog baseband circuitry, up-conversion circuitryand filtering and amplification circuitry, the latter of which mayprovide an amount of amplification that is controlled by an automaticgain control (AGC). In another aspect, the transmit circuitry mayinclude digital transmit circuitry and output circuitry.

The radio frequency circuitry may include one or more instances of radiochain circuitry, which in some aspects may include one or more filters,power amplifiers, low noise amplifiers, programmable phase shifters andpower supplies. The radio frequency circuitry may include powercombining and dividing circuitry in some aspects. In some aspects, thepower combining and dividing circuitry may operate bidirectionally, suchthat the same physical circuitry may be configured to operate as a powerdivider when the device is transmitting, and as a power combiner whenthe device is receiving. In some aspects, the power combining anddividing circuitry may one or more include wholly or partially separatecircuitries to perform power dividing when the device is transmittingand power combining when the device is receiving. In some aspects, thepower combining and dividing circuitry may include passive circuitrycomprising one or more two-way power divider/combiners arranged in atree. In some aspects, the power combining and dividing circuitry mayinclude active circuitry comprising amplifier circuits.

In some aspects, the radio frequency circuitry may connect to transmitcircuitry and receive circuitry via one or more radio chain interfacesor a combined radio chain interface. In some aspects, one or more radiochain interfaces may provide one or more interfaces to one or morereceive or transmit signals, each associated with a single antennastructure which may comprise one or more antennas.

In some aspects, the combined radio chain interface may provide a singleinterface to one or more receive or transmit signals, each associatedwith a group of antenna structures comprising one or more antennas.

The receive circuitry may include one or more of parallel receivecircuitry and/or one or more of combined receive circuitry. In someaspects, the one or more parallel receive circuitry and one or morecombined receive circuitry may include one or more IntermediateFrequency (IF) down-conversion circuitry, IF processing circuitry,baseband down-conversion circuitry, baseband processing circuitry andanalog-to-digital converter (ADC) circuitry.

In an aspect, the RF circuitry may include one or more of each of IFinterface circuitry, filtering circuitry, upconversion anddownconversion circuitry, synthesizer circuitry, filtering andamplification circuitry, power combining and dividing circuitry andradio chain circuitry.

In an aspect, the baseband processor may contain one or more digitalbaseband systems. In an aspect, the one or more digital basebandsubsystems may be coupled via an interconnect subsystem to one or moreof a CPU subsystem, audio subsystem and interface subsystem. In anaspect, the one or more digital baseband subsystems may be coupled viaanother interconnect subsystem to one or more of each of digitalbaseband interface and mixed-signal baseband sub-system. In an aspect,the interconnect subsystems may each include one or more of each ofbuses point-to-point connections and network-on-chip (NOC) structures.

In an aspect, an audio sub-system may include one or more of digitalsignal processing circuitry, buffer memory, program memory, speechprocessing accelerator circuitry, data converter circuitry such asanalog-to-digital and digital-to-analog converter circuitry, and analogcircuitry including one or more of amplifiers and filters. In an aspect,a mixed signal baseband sub-system may include one or more of an IFinterface, analog IF subsystem, downconverter and upconverter subsystem,analog baseband subsystem, data converter subsystem, synthesizer andcontrol sub-system.

A baseband processing subsystem may include one or more of each of DSPsub-systems, interconnect sub-system, boot loader sub-system, sharedmemory sub-system, digital I/O sub-system, digital baseband interfacesub-system and audio sub-system. In an example aspect, the basebandprocessing subsystem may include one or more of each of an acceleratorsubsystem, buffer memory, interconnect sub-system, audio sub-system,shared memory sub-system, digital I/O subsystem, controller sub-systemand digital baseband interface sub-system.

In an aspect, the boot loader sub-system may include digital logiccircuitry configured to perform configuration of the program memory andrunning state associated with each of the one or more DSP sub-systems.The configuration of the program memory of each of the one or more DSPsub-systems may include loading executable program code from storageexternal to baseband processing sub-system. The configuration of therunning state associated with each of the one or more DSP sub-systemsmay include one or more of the steps of: setting the state of at leastone DSP core which may be incorporated into each of the one or more DSPsub-systems to a state in which it is not running, and setting the stateof at least one DSP core which may be incorporated into each of the oneor more DSP sub-systems into a state in which it begins executingprogram code starting from a predefined memory location.

In an aspect, the shared memory sub-system may include one or more of aread-only memory (ROM), static random access memory (SRAM), embeddeddynamic random access memory (eDRAM) and non-volatile random accessmemory (NVRAM). In an aspect, the digital I/O subsystem may include oneor more of serial interfaces such as I²C, SPI or other 1, 2 or 3-wireserial interfaces, parallel interfaces such as general-purposeinput-output (GPIO), register access interfaces and direct memory access(DMA). In an aspect, a register access interface implemented in digitalI/O subsystem may permit a microprocessor core external to basebandprocessing subsystem (1000 cross reference) to read and/or write one ormore of control and data registers and memory. In an aspect, DMA logiccircuitry implemented in digital I/O subsystem may permit transfer ofcontiguous blocks of data between memory locations including memorylocations internal and external to baseband processing subsystem. In anaspect, the digital baseband interface sub-system may provide for thetransfer of digital baseband samples between the baseband processingsubsystem and mixed signal baseband or radio-frequency circuitryexternal to the baseband processing subsystem. In an aspect, the digitalbaseband samples transferred by the digital baseband interfacesub-system may include in-phase and quadrature (I/Q) samples.

In an aspect, the controller sub-system may include one or more of eachof control and status registers and control state machines. In anaspect, the control and status registers may be accessed via a registerinterface and may provide for one or more of: starting and stoppingoperation of control state machines, resetting control state machines toa default state, configuring optional processing features, configuringthe generation of interrupts and reporting the status of operations. Inan aspect, each of the one or more control state machines may controlthe sequence of operation of each of the one or more acceleratorsub-systems.

In an aspect, the DSP sub-system may include one or more of each of aDSP core sub-system, local memory, direct memory access sub-system,accelerator sub-system, external interface sub-system, power managementunit and interconnect sub-system. In an aspect, the local memory mayinclude one or more of each of read-only memory, static random accessmemory or embedded dynamic random access memory. In an aspect, thedirect memory access sub-system may provide registers and control statemachine circuitry adapted to transfer blocks of data between memorylocations including memory locations internal and external to thedigital signal processor sub-system. In an aspect, the externalinterface sub-system may provide for access by a microprocessor systemexternal to DSP sub-system to one or more of memory, control registersand status registers which may be implemented in the DSP sub-system. Inan aspect, the external interface sub-system may provide for transfer ofdata between local memory and storage external to the DSP sub-systemunder the control of one or more of the DMA sub-system and DSP coresub-system.

FIG. 4 is an illustration of protocol functions in accordance with someembodiments. The protocol functions may be implemented in a wirelesscommunication device according to some aspects. In some aspects, theprotocol layers may include one or more of physical layer (PHY) 410,medium access control layer (MAC) 420, radio link control layer (RLC)430, packet data convergence protocol layer (PDCP) 440, service dataadaptation protocol (SDAP) layer 447, radio resource control layer (RRC)455, and non-access stratum (NAS) layer 457, in addition to other higherlayer functions not illustrated.

According to some aspects, the protocol layers may include one or moreservice access points that may provide communication between two or moreprotocol layers. According to some aspects, the PHY 410 may transmit andreceive physical layer signals 405 that may be received or transmittedrespectively by one or more other communication devices. According tosome aspects, physical layer signals 405 may comprise one or morephysical channels.

According to some aspects, an instance of PHY 410 may process requestsfrom and provide indications to an instance of MAC 420 via one or morephysical layer service access points (PHY-SAP) 415. According to someaspects, requests and indications communicated via PHY-SAP 415 maycomprise one or more transport channels.

According to some aspects, an instance of MAC 410 may process requestsfrom and provide indications to an instance of RLC 430 via one or moremedium access control service access points (MAC-SAP) 425. According tosome aspects, requests and indications communicated via MAC-SAP 425 maycomprise one or more logical channels.

According to some aspects, an instance of RLC 430 may process requestsfrom and provide indications to an instance of PDCP 440 via one or moreradio link control service access points (RLC-SAP) 435. According tosome aspects, requests and indications communicated via RLC-SAP 435 maycomprise one or more RLC channels.

According to some aspects, an instance of PDCP 440 may process requestsfrom and provide indications to one or more of an instance of RRC 455and one or more instances of SDAP 447 via one or more packet dataconvergence protocol service access points (PDCP-SAP) 445. According tosome aspects, requests and indications communicated via PDCP-SAP 445 maycomprise one or more radio bearers.

According to some aspects, an instance of SDAP 447 may process requestsfrom and provide indications to one or more higher layer protocolentities via one or more service data adaptation protocol service accesspoints (SDAP-SAP) 449. According to some aspects, requests andindications communicated via SDAP-SAP 449 may comprise one or morequality of service (QoS) flows.

According to some aspects, RRC entity 455 may configure, via one or moremanagement service access points (M-SAP), aspects of one or moreprotocol layers, which may include one or more instances of PHY 410, MAC420, RLC 430, PDCP 440 and SDAP 447. According to some aspects, aninstance of RRC 455 may process requests from and provide indications toone or more NAS entities via one or more RRC service access points(RRC-SAP) 456.

FIG. 5 is an illustration of protocol entities in accordance with someembodiments. The protocol entities may be implemented in wirelesscommunication devices, including one or more of a user equipment (UE)560, a base station, which may be termed an evolved node B (eNB), or newradio node B (gNB) 580, and a network function, which may be termed amobility management entity (MME), or an access and mobility managementfunction (AMF) 594, according to some aspects.

According to some aspects, gNB 580 may be implemented as one or more ofa dedicated physical device such as a macro-cell, a femto-cell or othersuitable device, or in an alternative aspect, may be implemented as oneor more software entities running on server computers as part of avirtual network termed a cloud radio access network (CRAN).

According to some aspects, one or more protocol entities that may beimplemented in one or more of UE 560, gNB 580 and AMF 594, may bedescribed as implementing all or part of a protocol stack in which thelayers are considered to be ordered from lowest to highest in the orderPHY, MAC, RLC, PDCP, RRC and NAS. According to some aspects, one or moreprotocol entities that may be implemented in one or more of UE 560, gNB580 and AMF 594, may communicate with a respective peer protocol entitythat may be implemented on another device, using the services ofrespective lower layer protocol entities to perform such communication.

According to some aspects, UE PHY 572 and peer entity gNB PHY 590 maycommunicate using signals transmitted and received via a wirelessmedium. According to some aspects, UE MAC 570 and peer entity gNB MAC588 may communicate using the services provided respectively by UE PHY572 and gNB PHY 590. According to some aspects, UE RLC 568 and peerentity gNB RLC 586 may communicate using the services providedrespectively by UE MAC 570 and gNB MAC 588. According to some aspects,UE PDCP 566 and peer entity gNB PDCP 584 may communicate using theservices provided respectively by UE RLC 568 and NGNB RLC 586. Accordingto some aspects, UE RRC 564 and gNB RRC 582 may communicate using theservices provided respectively by UE PDCP 566 and gNB PDCP 584.According to some aspects, UE NAS 562 and AMF NAS 592 may communicateusing the services provided respectively by UE RRC 564 and gNB RRC 582.

The UE and gNB may communicate using a radio frame structure that has apredetermined duration and repeats in a periodic manner with arepetition interval equal to the predetermined duration. The radio framemay be divided into two or more subframes. In an aspect, subframes maybe of predetermined duration which may be unequal. In an alternativeaspect, subframes may be of a duration which is determined dynamicallyand varies between subsequent repetitions of the radio frame. In anaspect of frequency division duplexing (FDD), the downlink radio framestructure is transmitted by a base station to one or devices, and uplinkradio frame structure transmitted by a combination of one or moredevices to a base station. The radio frame may have a duration of 10 ms.The radio frame may be divided into slots each of duration 0.5 ms, andnumbered from 0 to 19. Additionally, each pair of adjacent slotsnumbered 2i and 2i+1, where i is an integer, may be referred to as asubframe. Each subframe may include a combination of one or more ofdownlink control information, downlink data information, uplink controlinformation and uplink data information. The combination of informationtypes and direction may be selected independently for each subframe.

According to some aspects, the downlink frame and uplink frame may havea duration of 10 ms, and uplink frame may be transmitted with a timingadvance with respect to downlink frame. According to some aspects, thedownlink frame and uplink frame may each be divided into two or moresubframes, which may be 1 ms in duration. According to some aspects,each subframe may consist of one or more slots. In some aspects, thetime intervals may be represented in units of T_(s). According to someaspects, T_(s) may be defined as 1/(30,720×1000) seconds. According tosome aspects, a radio frame may be defined as having duration30,720·T_(s), and a slot may be defined as having duration 15,360·T_(s).According to some aspects, T_(s) may be defined asT _(s)=1/(Δf _(max) ·N _(f)),where Δf_(max)=480×10³ and Nf=4,096. According to some aspects E, thenumber of slots may be determined based on a numerology parameter, whichmay be related to a frequency spacing between subcarriers of amulticarrier signal used for transmission.

Constellation designs of a single carrier modulation scheme that may betransmitted or received may contain 2 points, known as binary phaseshift keying (BPSK), 4 points, known as quadrature phase shift keying(QPSK), 16 points, known as quadrature amplitude modulation (QAM) with16 points (16QAM or QAM16) or higher order modulation constellations,containing for example 64, 256 or 1024 points. In the constellations,the binary codes are assigned to the points of the constellation using ascheme such that nearest-neighbor points, that is, pairs of pointsseparated from each other by the minimum Euclidian distance, have anassigned binary code differing by only one binary digit. For example,the point assigned code 1000 has nearest neighbor points assigned codes1001, 0000, 1100 and 1010, each of which differs from 1000 by only onebit.

Alternatively, the constellation points may be arranged in a squaregrid, and may be arranged such that there is an equal distance on thein-phase and quadrature plane between each pair of nearest-neighborconstellation points. In an aspect, the constellation points may bechosen such that there is a pre-determined maximum distance from theorigin of the in-phase and quadrature plane of any of the allowedconstellation points, the maximum distance represented by a circle. Inan aspect, the set of allowed constellation points may exclude thosethat would fall within square regions at the corners of a square grid.The constellation points are shown on orthogonal in-phase and quadratureaxes, representing, respectively, amplitudes of sinusoids at the carrierfrequency and separated in phase from one another by 90 degrees. In anaspect, the constellation points are grouped into two or more sets ofconstellation points, the points of each set being arranged to have anequal distance to the origin of the in-phase and quadrature plane, andlying on one of a set of circles centered on the origin.

To generate multicarrier baseband signals for transmission, data may beinput to an encoder to generate encoded data. The encoder may include acombination of one or more of error detecting, error correcting, ratematching, and interleaving. The encoder may further include a step ofscrambling. In an aspect, encoded data may be input to a modulationmapper to generate complex valued modulation symbols. The modulationmapper may map groups containing one or more binary digits, selectedfrom the encoded data, to complex valued modulation symbols according toone or more mapping tables. In an aspect, complex-valued modulationsymbols may be input to the layer mapper to be mapped to one or morelayer mapped modulation symbol streams. Representing a stream ofmodulation symbols 440 as d(i) where i represents a sequence numberindex, and the one or more streams of layer mapped symbols as x^((k))(i)where k represents a stream number index and i represents a sequencenumber index, the layer mapping function for a single layer may beexpressed as:x ⁽⁰⁾(i)=d(i)and the layer mapping for two layers may be expressed as:x ⁽⁰⁾(i)=d(2i)x ⁽¹⁾(i)=d(2i+1)

Layer mapping may be similarly represented for more than two layers.

In an aspect, one or more streams of layer mapped symbols may be inputto the precoder which generates one or more streams of precoded symbols.Representing the one or more streams of layer mapped symbols as a blockof vectors:[x ⁽⁰⁾(i) . . . x ^((v−1))(i)]^(T)where i represents a sequence number index in the range 0 to M_(symb)^(layer)−1 the output is represented as a block of vectors:[z ⁽⁰⁾(i) . . . z ^((P−1))(i)]^(T)where i represents a sequence number index in the range 0 to M_(symb)^(ap)−1. The precoding operation may be configured to include one ofdirect mapping using a single antenna port, transmit diversity usingspace-time block coding, or spatial multiplexing.

In an aspect, each stream of precoded symbols may be input to a resourcemapper which generates a stream of resource mapped symbols. The resourcemapper may map precoded symbols to frequency domain subcarriers and timedomain symbols according to a mapping which may include contiguous blockmapping, randomized mapping or sparse mapping according to a mappingcode.

In an aspect, the resource mapped symbols may be input to multicarriergenerator which generates a time domain baseband symbol. Multicarriergenerator may generate time domain symbols using, for example, aninverse discrete Fourier transform (DFT), commonly implemented as aninverse fast Fourier transform (FFT) or a filter bank comprising one ormore filters. In an aspect, where resource mapped symbols 455 arerepresented as s_(k)(i), where k is a subcarrier index and i is a symbolnumber index, a time domain complex baseband symbol x(t) may berepresented as:

${x(t)} = {\sum\limits_{k}{{s_{k}(i)}{p_{T}\left( {t - T_{sym}} \right)}{\exp\left\lbrack {j\; 2\pi\;{f_{k}\left( {t - T_{sym} - \tau_{k}} \right)}} \right\rbrack}}}$

Where p_(T)(t) is a prototype filter function, T_(sym) is the start timeof the symbol period, τ_(k) is a subcarrier dependent time offset, andf_(k) is the frequency of subcarrier k. Prototype functions p_(T)(t) maybe, for example, rectangular time domain pulses, Gaussian time domainpulses or any other suitable function.

In some aspects, a sub-component of a transmitted signal consisting ofone subcarrier in the frequency domain and one symbol interval in thetime domain may be termed a resource element. Resource elements may bedepicted in a grid form. In some aspects, resource elements may begrouped into rectangular resource blocks consisting of 12 subcarriers inthe frequency domain and the P symbols in the time domain, where P maycorrespond to the number of symbols contained in one slot, and may be 6,7, or any other suitable number of symbols. In some alternative aspects,resource elements may be grouped into resource blocks consisting of 12subcarriers in the frequency domain and one symbol in the time domain.Each resource element 05 may be indexed as (k, 1) where k is the indexnumber of subcarrier, in the range 0 to N·M−1, where N is the number ofsubcarriers in a resource block, and M is the number of resource blocksspanning a component carrier in the frequency domain.

In some aspects, coding of the signal to be transmitted may include oneor more physical coding processes that may be used to provide coding fora physical channel that may encode data or control information. Codingmay also include multiplexing and interleaving that generates combinedcoded information by combining information from one or more sources,which may include one of more of data information and controlinformation, and which may have been encoded by one or more physicalcoding processes. The combined coded information may be input to ascrambler which may generate scrambled coded information. Physicalcoding process may include one or more of CRC attachment, code blocksegmentation, channel coding, rate matching and code blockconcatenation. An encoder that may be used to encode data according toone of a convolutional code and a tail-biting convolutional code.

A MAC entity that may be used to implement medium access control layerfunctions may include one or more of a controller, a logical channelprioritizing unit, a channel multiplexer & de-multiplexer, a PDU filterunit, random access protocol entity, data hybrid automatic repeatrequest protocol (HARQ) entity and broadcast HARQ entity. According tosome aspects, a higher layer may exchange control and status messageswith controller via management service access point. According to someaspects, MAC service data units (SDU) corresponding to one or morelogical channels may be exchanged with the MAC entity via one or moreservice access points (SAP). According to some aspects, a PHY SDUcorresponding to one or more transport channels may be exchanged with aphysical layer entity via one or more SAPs. According to some aspects,the logical channel prioritization unit may perform prioritizationamongst one or more logical channels, which may include storingparameters and state information corresponding to each of the one ormore logical channels, that may be initialized when a logical channel isestablished. According to some aspects, the logical channelprioritization unit may be configured with a set of parameters for eachof one or more logical channels, each set including parameters which mayinclude one or more of a prioritized bit rate (PBR) and a bucket sizeduration (BSD).

According to some aspects, the multiplexer & de-multiplexer may generateMAC PDUs, which may include one or more of MAC-SDUs or partial MAC-SDUscorresponding to one or more logical channels, a MAC header which mayinclude one or more MAC sub-headers, one or more MAC control elements,and padding data. According to some aspects, the multiplexer &de-multiplexer may separate one or more MAC-SDUs or partial MAC-SDUscontained in a received MAC PDU, corresponding to one or more logicalchannels, and may indicate the one or more MAC-SDUs or partial MAC-SDUsto a higher layer via one or more service access points. According tosome aspects, the HARQ entity and broadcast HARQ entity may include oneor more parallel HARQ processes, each of which may be associated with aHARQ identifier, and which may be one of a receive or transmit HARQprocess.

According to some aspects, a transmit HARQ process may generate atransport block (TB) to be encoded by the PHY according to a specifiedredundancy version (RV), by selecting a MAC-PDU for transmission.According to some aspects, a transmit HARQ process that is included in abroadcast HARQ entity may retransmit a same TB in successive transmitintervals a predetermined number of times. According to some aspects, atransmit HARQ process included in a HARQ entity may determine whether toretransmit a previously transmitted TB or to transmit a new TB at atransmit time based on whether a positive acknowledgement or a negativeacknowledgement was received for a previous transmission.

According to some aspects, a receive HARQ process may be provided withencoded data corresponding to one or more received TBs and which may beassociated with one or more of a new data indication (NDI) and aredundancy version (RV), and the receive HARQ process may determinewhether each such received encoded data block corresponds to aretransmission of a previously received TB or a not previously receivedTB. According to some aspects, a receive HARQ process may include abuffer, which may be implemented as a memory or other suitable storagedevice, and may be used to store data based on previously received datafor a TB. According to some aspects, a receive HARQ process may attemptto decode a TB, the decoding based on received data for the TB, andwhich may be additionally be based on the stored data based onpreviously received data for the TB.

FIG. 6 illustrates an architecture of a system of a network inaccordance with some embodiments. The system 600 is shown to include auser equipment (UE) 601 and a UE 602. The UEs 601 and 602 areillustrated as smartphones (e.g., handheld touchscreen mobile computingdevices connectable to one or more cellular networks), but may alsocomprise any mobile or non-non-mobile computing device, such as PersonalData Assistants (PDAs), pagers, laptop computers, desktop computers,wireless handsets, or any computing device including a wirelesscommunications interface.

In some embodiments, any of the UEs 601 and 602 can comprise an Internetof Things (IoT) UE, which can comprise a network access layer designedfor low-power IoT applications utilizing short-lived UE connections. AnIoT UE can utilize technologies such as machine-to-machine (M2M) or MTCfor exchanging data with an MTC server or device via a public landmobile network (PLMN), Proximity-Based Service (ProSe) ordevice-to-device (D2D) communication, sensor networks, or IoT networks.The M2M or MTC exchange of data may be a machine-initiated exchange ofdata. An IoT network describes interconnecting IoT UEs, which mayinclude uniquely identifiable embedded computing devices (within theInternet infrastructure), with short-lived connections. The IoT UEs mayexecute background applications (e.g., keep-alive messages, statusupdates, etc.) to facilitate the connections of the IoT network.

The UEs 601 and 602 may be configured to connect, e.g., communicativelycouple, with a radio access network (RAN) 610—the RAN 610 may be, forexample, an Evolved Universal Mobile Telecommunications System (UMTS)Terrestrial Radio Access Network (E-UTRAN), a NextGen RAN (NG RAN), orsome other type of RAN. The UEs 601 and 602 utilize connections 603 and604, respectively, each of which comprises a physical communicationsinterface or layer (discussed in further detail below); in this example,the connections 603 and 604 are illustrated as an air interface toenable communicative coupling, and can be consistent with cellularcommunications protocols, such as a Global System for MobileCommunications (GSM) protocol, a code-division multiple access (CDMA)network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular(POC) protocol, a Universal Mobile Telecommunications System (UMTS)protocol, a 3GPP Long Term Evolution (LTE) protocol, a NG protocol, andthe like.

In this embodiment, the UEs 601 and 602 may further directly exchangecommunication data via a ProSe interface 605. The ProSe interface 605may alternatively be referred to as a sidelink interface comprising oneor more logical channels, including but not limited to a PhysicalSidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel(PSSCH), a Physical Sidelink Discovery Channel (PSDCH), and a PhysicalSidelink Broadcast Channel (PSBCH).

The UE 602 is shown to be configured to access an access point (AP) 606via connection 607. The connection 607 can comprise a local wirelessconnection, such as a connection consistent with any IEEE 802.11protocol, wherein the AP 606 would comprise a wireless fidelity (WiFi)router. In this example, the AP 606 is shown to be connected to theInternet without connecting to the core network of the wireless system(described in further detail below).

The RAN 610 can include one or more access nodes that enable theconnections 603 and 604. These access nodes (ANs) can be referred to asbase stations (BSs), NodeBs, evolved NodeBs (eNBs), next GenerationNodeBs (gNBs), RAN nodes, and so forth, and can comprise ground stations(e.g., terrestrial access points) or satellite stations providingcoverage within a geographic area (e.g., a cell). The RAN 610 mayinclude one or more RAN nodes for providing macrocells, e.g., macro RANnode 611, and one or more RAN nodes for providing femtocells orpicocells (e.g., cells having smaller coverage areas, smaller usercapacity, or higher bandwidth compared to macrocells), e.g., low power(LP) RAN node 612.

Any of the RAN nodes 611 and 612 can terminate the air interfaceprotocol and can be the first point of contact for the UEs 601 and 602.In some embodiments, any of the RAN nodes 611 and 612 can fulfillvarious logical functions for the RAN 610 including, but not limited to,radio network controller (RNC) functions such as radio bearermanagement, uplink and downlink dynamic radio resource management anddata packet scheduling, and mobility management.

In accordance with some embodiments, the UEs 601 and 602 can beconfigured to communicate using Orthogonal Frequency-DivisionMultiplexing (OFDM) communication signals with each other or with any ofthe RAN nodes 611 and 612 over a multicarrier communication channel inaccordance various communication techniques, such as, but not limitedto, an Orthogonal Frequency-Division Multiple Access (OFDMA)communication technique (e.g., for downlink communications) or a SingleCarrier Frequency Division Multiple Access (SC-FDMA) communicationtechnique (e.g., for uplink and ProSe or sidelink communications),although the scope of the embodiments is not limited in this respect.The OFDM signals can comprise a plurality of orthogonal subcarriers.

The physical downlink shared channel (PDSCH) may carry user data andhigher-layer signaling to the UEs 601 and 602. The physical downlinkcontrol channel (PDCCH) may carry information about the transport formatand resource allocations related to the PDSCH channel, among otherthings. It may also inform the UEs 601 and 602 about the transportformat, resource allocation, and H-ARQ (Hybrid Automatic Repeat Request)information related to the uplink shared channel. Typically, downlinkscheduling (assigning control and shared channel resource blocks to theUE 602 within a cell) may be performed at any of the RAN nodes 611 and612 based on channel quality information fed back from any of the UEs601 and 602. The downlink resource assignment information may be sent onthe PDCCH used for (e.g., assigned to) each of the UEs 601 and 602.

Some embodiments may use concepts for resource allocation for controlchannel information that are an extension of the above-describedconcepts. For example, some embodiments may utilize an enhanced physicaldownlink control channel (EPDCCH) that uses PDSCH resources for controlinformation transmission. The EPDCCH may be transmitted using one ormore enhanced the control channel elements (ECCEs). Similar to above,each ECCE may correspond to nine sets of four physical resource elementsknown as an enhanced resource element groups (EREGs). An ECCE may haveother numbers of EREGs in some situations.

The RAN 610 is shown to be communicatively coupled to a core network(CN) 620—via an S1 or NG interface 613. In embodiments, the CN 620 maybe an evolved packet core (EPC) network, a NGC network, or some othertype of CN. In this embodiment, the S1 interface 613 is split into twoparts: the S1-U interface 614, which carries traffic data between theRAN nodes 611 and 612 and the serving gateway (S-GW) 622, and theS1-mobility management entity (MME) interface 615, which is a signalinginterface between the RAN nodes 611 and 612 and MMEs 621.

In this embodiment, the CN 620 comprises the MMEs 621, the S-GW 622, thePacket Data Network (PDN) Gateway (P-GW) 623, and a home subscriberserver (HSS) 624. The MMEs 621 may be similar in function to the controlplane of legacy Serving General Packet Radio Service (GPRS) SupportNodes (SGSN). The MMEs 621 may manage mobility aspects in access such asgateway selection and tracking area list management. The HSS 624 maycomprise a database for network users, including subscription-relatedinformation to support the network entities' handling of communicationsessions. The CN 620 may comprise one or several HSSs 624, depending onthe number of mobile subscribers, on the capacity of the equipment, onthe organization of the network, etc. For example, the HSS 624 canprovide support for routing/roaming, authentication, authorization,naming/addressing resolution, location dependencies, etc.

The S-GW 622 may terminate the S1 interface 613 towards the RAN 610, androutes data packets between the RAN 610 and the CN 620. In addition, theS-GW 622 may be a local mobility anchor point for inter-RAN nodehandovers and also may provide an anchor for inter-3GPP mobility. Otherresponsibilities may include lawful intercept, charging, and some policyenforcement.

The P-GW 623 may terminate an SGi interface toward a PDN. The P-GW 623may route data packets between the EPC network 623 and external networkssuch as a network including the application server 630 (alternativelyreferred to as application function (AF)) via an Internet Protocol (IP)interface 625. Generally, the application server 630 may be an elementoffering applications that use IP bearer resources with the core network(e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). Inthis embodiment, the P-GW 623 is shown to be communicatively coupled toan application server 630 via an IP communications interface 625. Theapplication server 630 can also be configured to support one or morecommunication services (e.g., Voice-over-Internet Protocol (VoIP)sessions, PTT sessions, group communication sessions, social networkingservices, etc.) for the UEs 601 and 602 via the CN 620.

The P-GW 623 may further be a node for policy enforcement and chargingdata collection. Policy and Charging Rules Function (PCRF) 626 is thepolicy and charging control element of the CN 620. In a non-roamingscenario, there may be a single PCRF in the Home Public Land MobileNetwork (HPLMN) associated with a UE's Internet Protocol ConnectivityAccess Network (IP-CAN) session. In a roaming scenario with localbreakout of traffic, there may be two PCRFs associated with a UE'sIP-CAN session: a Home PCRF (H-PCRF) within a HPLMN and a Visited PCRF(V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF626 may be communicatively coupled to the application server 630 via theP-GW 623. The application server 630 may signal the PCRF 626 to indicatea new service flow and select the appropriate Quality of Service (QoS)and charging parameters. The PCRF 626 may provision this rule into aPolicy and Charging Enforcement Function (PCEF) (not shown) with theappropriate traffic flow template (TFT) and QoS class of identifier(QCI), which commences the QoS and charging as specified by theapplication server 630.

The components of FIG. 6 are able to read instructions from amachine-readable or computer-readable medium (e.g., a non-transitorymachine-readable storage medium) and perform any one or more of themethodologies discussed herein. In particular, the processors (e.g., acentral processing unit (CPU), a reduced instruction set computing(RISC) processor, a complex instruction set computing (CISC) processor,a graphics processing unit (GPU), a digital signal processor (DSP) suchas a baseband processor, an application specific integrated circuit(ASIC), a radio-frequency integrated circuit (RFIC), another processor,or any suitable combination thereof) may read and follow theinstructions on a non-transitory medium.

Instructions may comprise software, a program, an application, anapplet, an app, or other executable code for causing at least any of theprocessors to perform any one or more of the methodologies discussedherein. The instructions may reside, completely or partially, within atleast one of the processors (e.g., within the processor's cache memory),the memory/storage devices, or any suitable combination thereof. In someembodiments, the instructions may reside on a tangible, non-volatilecommunication device readable medium, which may include a single mediumor multiple media. Furthermore, any portion of the instructions may betransferred to the hardware resources from any combination of theperipheral devices or the databases 606. Accordingly, the memory ofprocessors, the memory/storage devices, the peripheral devices, and thedatabases are examples of computer-readable and machine-readable media.

The above discussion concentrates primarily on LTE networks, however, NGnetworks will soon start to be deployed, leading to various challenges.FIG. 7 illustrates a combined 4G and NG communication system inaccordance with some embodiments. Some elements may not be shown forconvenience. The 4G core network (EPC) contains, as above, protocol andreference points are defined for each entity such as the MME, SGW, andPGW. The NG (next generation) architecture as includes multiple networkfunctions (NFs) and reference points connecting the network functions. Anetwork function can be implemented as a discrete network element on adedicated hardware, as a software instance running on dedicatedhardware, or as a virtualized function instantiated on an appropriateplatform, e.g., dedicated hardware or a cloud infrastructure.

In FIG. 7, the UE 702 may be connected to a RAN 710 of an Evolved PacketCore (EPC) and/or a NG-RAN (gNB) 730 of a NG-CN. Note that the RAN andNG-RAN are identified differently in FIG. 7, in other circumstanceseither may be referred to herein simply as a RAN. The RAN 710 mayinclude one or more eNBs or general non-3GPP access points, such as thatfor Wi-Fi. Each of the one or more gNBs 730 may be a standalone gNB or anon-standalone gNB, e.g., operating in Dual Connectivity (DC) mode as abooster controlled by the eNB 710 through an X2 interface. The gNB 730may, for example, provide additional capacity within a predeterminedarea inside the area of the eNB 710. The eNB 710 may be connected withan MME 722 of the EPC through an S1-MME interface and with a SGW 724 ofthe EPC through an S1-U interface. The MME 722 may be connected with anHSS 728 through an S6a interface.

In the NG network, the control plane and the user plane may beseparated, which may permit independent scaling and distribution of theresources of each plane. The UE 702 may be connected to an Access andMobility Function (AMF) 742 of the NG CN. The NG CN may contain multiplenetwork functions besides the AMF 712. These functions may include aUser Plane Function (UPF) 746, a Session Management Function (SMF) 744,a Policy Control Function (PCF) 732, an Application Function (AF) 720,an Authentication Server Function (AUSF) 740 and User Data Management(UDM) 728. The various elements may be connected by the reference pointsshown in FIG. 7. At least some of functionality of the EPC and the NG CNmay be shared. Alternatively, separate components may be used for eachof the combined component shown.

The AMF 712 may provide mobility-related functionality similar to thatof the MME 722. This functionality may include UE-based authentication,authorization and mobility management, for example. The AMF 712 may beindependent of the access technologies. The SMF 714 and UPF 706 maysplit the NG control and user functionality of the PGW 726. The SMF 714may be responsible for session management and allocation of IP addressesto the UE 702. The SMF 714 may also select and control the UPF 706 fordata transfer, including the establishment of filters in the UPF 706.

The SMF 714 may be associated with a single session of the UE 702 ormultiple sessions of the UE 702. This is to say that the UE 702 may havemultiple NG sessions. In some embodiments, different SMFs may beallocated to each session. The use of different SMFs may permit eachsession to be individually managed. As a consequence, thefunctionalities of each session may be independent of each other. TheUPF 746 may be connected with a data network, with which the UE 702 maycommunicate, the UE 702 transmitting uplink data to or receivingdownlink data from the data network.

The AF 720 may provide information on the packet flow to the PCF 732responsible for policy control to support a desired QoS. The AF 720 maysend service requests and CODEC (Coding-Decoding, orCompression-Decompression) parameters to a Policy and Charging Rulesfunction (PCRF) 732. The PCF 732 may set mobility and session managementpolicies for the UE 702. To this end, the PCF 732 may use the packetflow information to determine the appropriate policies for properoperation of the AMF 742 and SMF 744. The AUSF 740 may store data for UEauthentication.

The UDM 728 (which may be shared with the HSS) may similarly store theUE subscription data. The UDM 728 may be connected to the AMF 742through the N8 interface. The SGW 724 may connected with the PGW 726through an S5 interface (control plane PGW-C through S5-C and user planePGW-U through S5-U). The PGW 726 may serve as an IP anchor for datathrough the internet.

The eNB 710 and gNB 730 may communicate data with the SGW 724 of the EPCand the UPF 746 of the NG CN. The MME 722 and the AMF 742 may beconnected via the N26 interface to provide control informationtherebetween, if the N26 interface is supported by the EPC. The PCF andPCRF 732 may be combined and connected to the AMF 742 through the N15interface.

The UE may be able to take advantage of a dual-connectivity (DC)framework, in which the UE may be connected simultaneously with a masterNodeB (MNB) and a secondary NodeB (SNB). The MNB and SNB may be eNBs,gNBs, or a combination thereof, for example. In some embodiments, theMNB may use a single SNB for a bearer associated with the UE. In someembodiments, the MNB may service the UE, so that all UL and DL data flowassociated with the bearer is controlled by the MNB. For example, theMNB may transmit packets to the SNB for delivery to the UE. The SNB mayprovide the MNB with information about packet transmission or deliveryto permit the MNB to control packet flow to the SNB to avoid overflow orunderflow buffer issues associated with packet delivery to the UE. Thepacket and control flow may be transmitted over an X2 interface when theMNB and SNB are eNBs over an Xn interface when the MNB and SNB are gNBs(although a combination of eNB and gNB may be used as well). FIG. 8illustrates interconnections for gNBs in accordance with someembodiments.

As shown in FIG. 8, the gNBs 810 a, 810 b are each connected withdifferent AMFs 802 and UPFs 804 through an NG-Control plane (NG-C or, asindicated in FIG. 7, N2) interface and an NG-User plane (NG-U or, asindicated in FIG. 7, N3) interface, respectively. The gNBs 810 a, 810 bmay be connected with each other via dual Xn interfaces for controlplane signaling (Xn-C) and user plane signaling (Xn-U). The controlplane functions of the Xn-C interface may include interface managementand error handling functionality, connected mode mobility management,support of RAN paging and dual connectivity functions, among others.Examples of the interface management and error handling functionalityinclude setup, reset, removal and configuration update of the Xninterface. Examples of connected mode mobility management includehandover procedures, sequence number status transfer and UE contextretrieval. Examples of dual connectivity functions include secondarynode addition, reconfiguration, modification, and release of thesecondary node. The user plane functions of the Xn-U interface mayinclude both data forwarding and flow control between the gNBs 810 a,810 b.

Each of the gNBs 810 a, 810 b may implement protocol entities in theprotocol stack shown in FIG. 5, in which the layers are considered to beordered, from lowest to highest, in the order PHY, MAC, RLC, PDCP, andRRC/SDAP (for the control plane/user plane). The protocol layers in eachgNB 810 a, 810 b may be distributed in different units—a Central Unit812, at least one Distributed Unit 814, and a Remote Radio Head 816. TheCentral Unit 812 may provide functionalities such as the control thetransfer of user data, and effect mobility control, radio access networksharing, positioning, and session management, except those functionsallocated exclusively to the Distributed Unit 814.

In one particular embodiment, the higher protocol layers (PDCP and RRCfor the control plane/PDCP and SDAP for the user plane) may beimplemented in the Central Unit 812, and the RLC and MAC layers may beimplemented in the Distributed Unit 814. The PHY layer may be split,with the higher PHY layer also implemented in the Distributed Unit 814,while the lower PHY layer is implemented in the Remote Radio Head 816.The Central Unit 812, Distributed Unit 814 and Remote Radio Head 816 maybe implemented by different manufacturers, but may nevertheless beconnected by the appropriate interfaces therebetween. The Central Unit812 may be connected with multiple Distributed Units 814.

The interfaces within the gNB include the E1, and front-haul (F) F1 andF2 interfaces. The E1 Interface may be between a Central Unit controlplane and the Central Unit user plane and thus may support the exchangeof signaling information between the control plane and the user plane.The E1 Interface may separate Radio Network Layer and Transport NetworkLayer and enable exchange of UE associated information and non-UEassociated information. The F1 interface may be disposed between theCentral Unit 812 and the Distributed Unit 814. The Central Unit 812 maycontrol the operation of the Distributed Unit 814 over the F1 interface.

As the signaling in the gNB is split into control plane and user planesignaling, the F1 interface may be split into the F1-C interface forcontrol plane signaling and the F1-U interface for user plane signaling,which support control plane and user plane separation. The F1 interface,as above may separate the Radio Network and Transport Network Layers andenable exchange of UE associated information and non-UE associatedinformation.

The F2 interface may be between the lower and upper parts of the NR PHYlayer. The F2 interface may also be separated into F2-C and F2-Uinterfaces based on control plane and user plane functionalities.

Flow control for RAN interfaces was introduced as a Downlink (DL) DataDelivery Status (DDDS) message and extended with the addition of a DLDDDS Extended message to accommodate larger PDCP sequence numbers. Asimilar mechanism may be used for LTE-WLAN Aggregation (LWA) through theXw interface—the logical interface between the eNB and the WLANTermination (WT). However, there are a number of differences between theX2, Xw and Xn interfaces, leading to a desire to develop a flexible flowcontrol mechanism that are able to be used on multiple interfaces andcan be extended in the future, to support new interfaces and newfunctionality—rather than using different flow control mechanisms forthe different interfaces. It may be further desirable for such aflexible flow control mechanism to support the presence of optionalinformation.

Various embodiments may enable the above flexible flow controlmechanism, which may be used with at least the X2, Xw, Xn and F1/F2interfaces. Specifically, different DDDS frame structures may be used,depending on the embodiment. In a first embodiment, the DDDS framestructure may be expanded to add a sufficient number of spare bytes toallow optional fields to be indicated by a separate bit. In such anembodiment, a semantic description of fields (e.g. sequence numbers) maybe generalized to accommodate different interfaces. In a secondembodiment, Abstract Syntax Notation One (ASN.1) may be adopted for theDDDS frame structure. In a third embodiment, the type-length-value (TLV)(also known as tag-length-value) approach may be adopted for the DDDSmessage.

FIG. 9 illustrates information flow between nodes in accordance withsome embodiments. As shown, the node hosting the NR PDCP entity (i.e.,the transmitting node/node transmitting the NR PDCP PDUs) 902 maytransmit DL data for the UE to the corresponding node (i.e., thereceiving node/node receiving the NR PDCP PDUs) 904 for transmission tothe UE on the corresponding bearer. In response, the corresponding node904 may transmit a DDDS message having a particular frame format to thetransmitting node 902. In the first embodiment, a DL DDS (PDU Type 1)frame format may be defined to transfer feedback in a DDDS message toallow the transmitting node 902 to control the downlink user data flowvia the corresponding node 904.

Bits Number of 7 6 5 4 3 2 1 0 Octets PDU Type Highest PDCP Highest PDCPFinal Frame Lost Packet 1 (=I) Transmitted Ind Delivered Ind Ind. ReportSpare 1 Spare 1 Highest successfully delivered PDCP Sequence Number 3Highest transmitted PDCP Sequence Number 3 Desired buffer size for thedata bearer 4 Minimum desired buffer size for the UE 4 Number of lostNG-RAN-U Sequence Number ranges reported 1 Start of lost NG-RAN-USequence Number range  6* End of lost NG-RAN-U Sequence Number range(Number of reported lost 5G-U SNranges) Spare extension 1-7

DDDS Format

The DDDS frame format contains a number of octets which each providedifferent information. The first octet contains 4 bits to indicate thePDU type (e.g., 0 for user data, 1 for the DDDS, 2 for assistanceinformation data). The highest PDCP transmitted indicator parameterindicates the presence of the highest transmitted PDCP Sequence Number(0=not present, 1=present) in a later set of octets. The highesttransmitted PDCP Sequence Number field may be several (e.g., 3) octets,if present, and may provide feedback about the transmitted status of thePDCP PDU sequence at the corresponding node (gNB) to the lower layers.

The highest PDCP delivered indicator parameter in the first octetindicates the presence of the highest successfully delivered PDCPSequence Number (0=not present, 1=present). The highest successfullydelivered PDCP sequence number may be several (e.g., 3) octets, ifpresent, and may provide feedback about the in-sequence delivery statusof PDCP PDUs at the corresponding node (gNB) towards the UE. The highestsuccessfully delivered PDCP sequence number field may occur, as shown,in the octets immediately preceding the highest transmitted PDCPSequence Number field.

The final frame indicator indicates whether the frame is the last DLstatus report (0=not the final frame, 1=final frame). That is that thereceived frame is the last DL status report received while a bearer isbeing released from the corresponding node and thus the correspondingnode knows that the bearer will be released before the DL status reportis signaled. When the indication indicates the last frame, the nodehosting the PDCP entity may consider that no more UL or DL data isexpected to be transmitted between the corresponding node and the UE.The lost packet report parameter indicates the presence of the number oflost Sequence Number ranges reported and the start and end of the lostsequence number range (0=not present, 1=present).

Multiple (e.g. 4) octets in the DDDS frame may also be reserved toindicate the desired buffer size for the radio data bearer for the UE.In some cases, if the buffer size is 0, the hosting node may stopsending data for the UE per bearer; if the value is greater than 0, thehosting node may send up to the amount of data per bearer beyond theHighest Delivered or Transmitted PDCP Sequence Number—e.g., dependent onthe delivery mode (acknowledged or unacknowledged). The data rate mayalso be provided in a separate field.

Additionally, up to a single octet may be used to convey the number oflost NG-RAN-U Sequence Number ranges. The number of lost NG-RAN-USequence Number ranges reported parameter may be present, in some casesif a lost packet report indication is included in the DDDS frame. Iflost NG-RAN-U Sequence Number ranges are reported, up to 6 octets in theDDDS frame may be used to indicate the start and end of the lostNG-RAN-U Sequence Number range reported to be lost. In some cases, eachof the start and end of the lost NG-RAN-U Sequence Number range mayoccupy 3 octets, if present.

One or more octets or portion of octets may be reserved as a spare field(or extension). The spare field may be used in future DDDS frames (i.e.,reserved for later versions). The spare field, for example, may be usedto provide additional indicators that indicate whether other fields inthe DDDS frame are present. Thus, for example, data in one or morefields in the DDDS frame which have previously been non-optional (suchas the highest transmitted or successfully delivered PDCP SequenceNumber) may now be optional (i.e., not included in the DDDS frame ifindicated as such). The spare field may be set to 0 by the sender, inwhich case the receiver may avoid interpreting the spare field.Similarly, when one or more additional indicators are used in the sparefield, if a particular indicator in the spare field indicates theabsence of data in a later optional field, the receiver may avoidinterpreting the later optional field as this data may be set to 0 (ormay not be included). In addition, the spare fields may also be used toadd padding to ensure that the NR user plane protocol PDU length(including padding and any future extension) is (n*4−2) octets, where nis a positive integer. In some embodiments, at least a portion of thesecond and/or third octet may contain a spare field.

The DDDS frame above may have additional fields not discussed. The DDDSformat may be flexible—for example, when the protocol is used on the Xninterface, the NR PDCP Sequence Number may be used for the highest PDCPtransmitted and delivered indicator; when the protocol is used on the X2interface, the LTE PDCP Sequence Number may be used.

The DDDS message may thus be used to transfer DL user data between RANnodes for a single data radio bearer only per instance. To this end,specific sequence number information at the transfer of user datacarrying, for example, a DL NR PDCP PDU, may be provided from the nodehosting the NR PDCP entity to the corresponding node. The node hostingthe NR PDCP entity (the transmitting node) may assign consecutive NR-Usequence numbers to each transferred NR-U PDU. The receiving node maydetect whether an NR-U packet was lost and determine the respectivesequence number after the receiving node has determined that therespective NR-U packet is lost. The receiving node may transfer theremaining NR PDCP PDUs towards the UE and determine the highest NR PDCPPDU sequence number of the NR PDCP PDU that was successfully deliveredin sequence towards the UE (when RLC Acknowledged Mode (AM) is used) andthe highest NR PDCP PDU sequence number of the NR PDCP PDU that wastransmitted to the lower layers. The receiving node may send the DDDSmessage if the Report Polling Flag is set, unless a situation ofoverload at the corresponding node is encountered. The transmitting nodemay indicate to the receiving node whether a particular NR-U packet is aretransmission of a NR PDCP PDU. The transmitting node can indicate tothe receiving node to either discard all NR PDCP PDUs up to andincluding a defined DL discard NR PDCP PDU SN or discard one or a numberof blocks of downlink NR PDCP PDUs.

In further embodiments, the spare field in the second octet may be usedto provide a data rate indicator, the Highest Delivered Retransmitted orHighest Retransmitted PDCP Sequence Number indicators, and a causereport indicator. The data rate indicator may be used to indicatewhether the data rate (the amount of data desired to be received inbytes in a specific amount of time (e.g., 1 s)) for a specific dataradio bearer established for the UE is included in the DDDS frame. Thedata rate may be 4 octets in length. The cause report indicator may beused to indicate whether the cause value for the DDDS frame is presentin the DDDS frame. The cause value may be 1 octet in length and may takevalues that indicate the occurrence of an event such as radio linkoutage/resumption or UL/DL radio link outage/resumption. The HighestDelivered Retransmitted or Highest Retransmitted PDCP Sequence Numberindicator may be used to indicate whether Highest DeliveredRetransmitted or Highest Retransmitted PDCP Sequence Number isrespectfully included in the DDDS frame. The Highest DeliveredRetransmitted or Highest Retransmitted PDCP Sequence Number may each be3 octets and may be similar to the Highest Delivered or HighestTransmitted PDCP Sequence Number, with the retransmission PDCP SNreplacing the PDCP SN.

In another embodiment, ASN.1 may be adopted for DDDS as NG-RAN networknodes support ASN.1 functionality. In the above DDDS format embodiment,each parameter may have different lengths dependent on PDU type. Forexample, the highest successfully delivered PDCP sequence number can beeither 12 bits or 15 bits or 18 bits, depending on the bearerconfiguration. This DDDS format may thus use entirely separate frameswith different PDU types. On the other hand, the same message can bestill used in ASN.1 with e.g. a choice type description.

IE type and Assigned IE/Group Name Presence Range reference Semanticsdescription Criticality Criticality Message Type M YES reject FinalFrame O BIT STRING This parameter indicates YES reject Indicator (1)whether the message is the last DL status report Highest O PDCP SN Thisparameter indicates YES reject successfully Length feedback about thein- delivered Type sequence delivery status PDCP SN (see below) of PDCPPDUs at the node transmitting this message towards the UE Highest O PDCPSN This parameter indicates YES reject transmitted Length feedback aboutPDCP PDCP SN Type PDUs transferred to RLC (see below) at the nodetransmitting this message Desired buffer O OCTET This parameterindicates YES reject size for the data STRING (4) the desired buffersize bearer for the concerned bearer Minimum O OCTET This parameterindicates YES reject desired buffer STRING (4) the minimum desired sizefor the UE buffer size for all bearers established for the UE LostNG-RAN-U 0 . . . <maxnoo This list indicates the YES reject SequencefLostNGRA number of NG-RAN-U Number List NUlist> Sequence Number rangesreported to be lost >Lost NG-RAN- EACH reject U Sequence Number RangeItem >>Start M OCTET This parameter indicates STRING (3) the start of anNG-RAN-U sequence number range >>End M OCTET This parameter indicatesSTRING (3) the end of an NG-RAN-U sequence number range

PDCP SN Length Type

IE/Group IE Type Semantics Name Presence Range and Reference DescriptionCHOICE PDCP M SN Length Type >12 bits >>PDCP M BIT STRING (SIZE Sequence(12)) Number >15bits >>PDCP M BIT STRING (SIZE Sequence (15)) Number >18bits >>PDCP M BIT STRING (SIZE Sequence (18)) Number

In some embodiments, a TLV approach may be adopted for the DDDS message.In this case, the message may be a sequence of type-length-value triplesfor each parameter. Unlike the ASN.1 embodiment, the TLV embodiment mayavoid use of a choice type description to support and differentiatedifferent lengths within a parameter.

Semantics Name Type Length description Final Frame Indicator 1 BITSTRING Highest successfully 2 Either BIT STRING (12) or delivered PDCPSN BIT STRING (15) or BIT STRING (18) Highest transmitted 3 Either BITSTRING (12) or PDCP SN BIT STRING (15) or BIT STRING (18) Desired buffersize 4 OCTET STRING for the data bearer Minimum desired buffer 5 OCTETSTRING size for the UE Lost NG-RAN-U 6 Sequence Number List Spare 7-32

TLV DDDS Format

As shown, the “Length” field, which follows the “Type” field maydirectly indicate the length of the indicator, thereby permittingflexibility in the DDDS format. Although not shown explicitly, the listof lost sequence numbers may be signaled as pairs (of fixed length) ofstart and end sequence numbers.

In some embodiments, the Length field above can be omitted for aspecific type, if specified in that manner. For example, the highestsuccessfully delivered PDCP SN, which can be either 12 bits or 15 bitsor 18 bits (or may be more than 18 bits in the future), can be supportedwithout the Length field, if separate types are defined for each lengthas below:

Semantics Name Type Length description Final Frame Indicator  1 BITSTRING Highest successfully delivered PDCP SN 12 bits  2 Omitted Highestsuccessfully delivered PDCP SN 15 bits  3 Omitted Highest successfullydelivered PDCP SN 18 bits  4 Omitted Highest transmitted PDCP SN 12 bits 5 Omitted Highest transmitted PDCP SN 15 bits  6 Omitted Highesttransmitted PDCP SN 18 bits  7 Omitted Desired buffer size for the databearer  8 OCTET STRING Minimum desired buffer size for the UE  9 OCTETSTRING Lost NG-RAN-U Sequence Number List 10 Spare 11-32

TLV DDDS Format 2

Independent of the format used for the DDDS frame, the DDDS frame mayprovide feedback from the receiving node to the transmitting node toallow the transmitting node to control the DL user data flow via thereceiving node for the respective data radio bearer, as well as tocontrol the successful delivery of DL control data to the receivingnode. The receiving node may also transfer UL user data for the dataradio bearer to the transmitting node together with a DDDS frame withinthe same GTP-U PDU. The DDDS frame may be generated, as other operationsof the RAN nodes described herein, by one or more processors of the RANnode executing instructions in a non-transitory computer-readablestorage medium that stores the instructions.

When the receiving node determines that the DDDS message is to betransmitted to the transmitting node, the DDDS message may include thehighest NR PDCP PDU sequence number successfully delivered in sequenceto the UE among those NR PDCP PDUs received from the transmitting nodewhen RLC AM is used. The highest NR PDCP PDU sequence number may excluderetransmission NR PDCP PDUs. The DDDS message may also include thedesired buffer size in bytes for the data radio bearer associated withthe DDDS message and may contain a minimum buffer size in bytes for thedata radio bearer associated with the DDDS message. The DDDS message mayfurther include the NR-U packets that were declared as being lost by thereceiving node and have not yet been reported to the transmitting nodewithin the DDDS message and the highest NR PDCP PDU sequence numbertransmitted to the lower layers among those NR PDCP PDUs received fromthe transmitting node (excluding retransmission NR PDCP PDUs). The lostNR-U packet information may include the number of lost NR PDCP PDUsequence number ranges, as well as the start and end of the NR PDCP PDUsequence number range.

Prior to transmission of the DDDS message, the receiving node may detectwhether the UE has initiated a successful RACH access for the databearer, after which the receiving node may transmit an initial DDDSmessage to the transmitting node. The DDDS message may be associatedwith the bearer. In some cases, the transmitting node may start sendingDL data before receiving the initial DDDS message. When the DDDS messageis sent before any NR PDCP PDU is transferred to lower layers, theinformation on the highest NR PDCP PDU sequence number successfullydelivered in sequence to the UE and the highest NR PDCP PDU sequencenumber transmitted to the lower layers may not be provided.

The DDDS message may also include a final frame that indicates whetherthe frame is the last DL status report received in the course ofreleasing a bearer from the receiving node. The final frame indicationmay be signaled when the receiving node knows that the bearer will bereleased before the DL status report is signaled. When the DDDS messagecontains the final frame indication, the transmitting node may determinethat that no further UL or DL data is expected to be transmitted betweenthe receiving node and the UE.

The transmitting node, after receiving the DDDS message, may determinefrom the desired buffer size field the amount of data to be sent. If thevalue of the desired buffer size is 0, the transmitting node mayterminate data transmission on the bearer. If the value of the desiredbuffer size is greater than 0, the transmitting node may send up to theamount of data indicated per bearer beyond the highest successfullydelivered NR PDCP SN (for RLC AM) or the highest transmitted NR PDCP SN(for RLM UM). The information of the buffer size may be valid until thenext DDDS message is received by the transmitting node. The transmittingnode may remove buffered NR PDCP PDUs dependent on the feedback oftransmitted and/or successfully delivered NR PDCP PDUs in the DDDSmessage, as well as determining what actions to take for NR PDCP PDUsreported other than those reported transmitted and/or successfullydelivered (e.g., retransmission or removal from the buffer). For RLC AM,after the highest NR PDCP PDU sequence number successfully delivered insequence is reported to the transmitting node, the receiving node mayremove the respective NR PDCP PDUs. For RLC UM, the receiving node mayremove the respective NR PDCP PDUs after transmission to lower layers.

EXAMPLES

Example 1 is an apparatus of a next generation radio access network(NG-RAN) node, the apparatus comprising: a memory; and processingcircuitry arranged to: determine that downlink (DL) new radio (NR)packet data convergence protocol (PDCP) packet data units (PDUs) for auser equipment (UE) are to be transmitted to another NG-RAN node fortransmission to the UE; generate, for transmission to the other NG-RANnode over an Xn-User plane (Xn-U) interface, the DL NR PDCP PDUs fortransmission to the UE; extract from a downlink Data Delivery Status(DDDS) frame received from the other NG-RAN node in response totransmission of the DL NR PDCP PDUs to the other NG-RAN node: a highestdelivered PDCP Sequence Number (SN) indicator parameter indicating apresence in the DDDS frame of a SN of a highest successfully deliveredDL NR PDCP PDU, of the DL NR PDCP PDUs, that is successfully deliveredto the UE, and a highest successfully delivered PDCP SN parameter thatprovides the SN of the highest successfully delivered DL NR PDCP PDU,when indicated to be present by the highest successfully delivered PDCPSN indicator parameter; and instruct the memory to remove a set ofstored DL NR PDCP PDUs of DL NR PDCP PDUs indicated by the DDDS frame asat least one of transmitted or successfully delivered DL NR PDCP PDUs,wherein the DDDS frame is usable for both X2 interface DDDS messages andXn interface DDDS messages.

In Example 2, the subject matter of Example 1 includes, wherein: theDDDS frame further comprises a PDU type parameter that indicates a typeof the DDDS frame, a final frame indicator parameter that indicateswhether the DDDS frame is a final DL status report before release of abearer corresponding to the DDDS frame, a highest PDCP transmittedindicator parameter that indicates a presence in the DDDS frame of a SNof a highest transmitted DL NR PDCP PDU, of the DL NR PDCP PDUs, that istransmitted to the UE, and a lost packet report parameter that indicateswhether a number of lost SN ranges reported and a start and end of alost SN range is present in the DDDS frame, and the highest deliveredPDCP SN indicator parameter, the highest transmitted PDCP SN parameter,the PDU type parameter, the final frame indicator parameter and the lostpacket report parameter are provided in a first octet of the DDDS frame.

In Example 3, the subject matter of Example 2 includes, wherein thehighest delivered PDCP SN indicator parameter, the highest transmittedPDCP SN parameter, the final frame indicator parameter and the lostpacket report parameter are each a single bit and the PDU type parameteris multiple bits.

In Example 4, the subject matter of Examples 1-3 includes, by the NG-RANnode, the spare field reserved for later versions of DDDS frames.

In Example 5, the subject matter of Examples 1-4 includes, wherein theDDDS frame further comprises: a highest transmitted PDCP SN field thatprovides feedback about a transmitted status of the PDCP PDU sequence tolower layers, a desired buffer size for a radio data bearercorresponding to the DDDS frame, a number of lost SN ranges, and a startand end of a lost SN range reported in the DDDS frame to be lost.

In Example 6, the subject matter of Example 5 includes, wherein: thedesired buffer size occurs in the DDDS frame after a first octet, thenumber of lost SN ranges occurs in the DDDS frame after the desiredbuffer size, and the start and end of a lost SN range occurs in the DDDSframe after the number of lost SN ranges.

In Example 7, the subject matter of Examples 5-6 includes, wherein: thedesired buffer size is 4 octets, the number of lost SN ranges is asingle octet, and the start and end of a lost SN range are each up to 6octets.

In Example 8, the subject matter of Examples 1-7 includes, wherein: theNG-RAN node comprises a central unit configured to control transfer ofuser data between the NG-RAN node and the other NG-RAN node, and effectmobility control, radio access network sharing, positioning, and sessionmanagement for the UE, a distributed unit and a remote radio head (RRH),the central unit is connected with the distributed unit through a F1interface, and the distributed unit connected with the RRH through an F2interface.

In Example 9, the subject matter of Example 8 includes, wherein aphysical layer (PHY) layer of the NG-RAN node is split between thedistributed unit and the RRH to implement PHY high layer functionalityin the distributed unit and PHY low layer functionality in the RRH.

In Example 10, the subject matter of Examples 8-9 includes, wherein: thecentral unit further comprises an E1 interface that supports a signalinginformation exchange between a control plane and a user plane of thecentral unit, the F1 interface comprises an F1-User plane (F1-U)interface for user plane signaling between the central unit and thedistributed unit and an F1-Control plane (F1-C) interface for controlplane signaling between the central unit and the distributed unit, andthe F2 interface comprises an F2-U interface for user plane signalingbetween the distributed unit and the RRH and an F2-C interface forcontrol plane signaling between the distributed unit and the RRH.

In Example 11, the subject matter of Examples 1-10 includes, wherein theprocessing circuitry comprises: a baseband processor configured toencode transmissions to, and decode transmissions from, the other NG-RANnode.

Example 12 is an apparatus of a next generation radio access network(NG-RAN) node, the apparatus comprising: processing circuitry arrangedto: encode, for transmission to a user equipment (UE) on a radio bearer,downlink (DL) new radio (NR) packet data convergence protocol (PDCP)packet data units (PDUs) from another NG-RAN node over an Xn-User plane(Xn-U) interface; determine transmission characteristics of the DL NRPDCP PDUs; and in response to reception of the DL NR PDCP PDUs, generatefeedback for transmission to the other NG-RAN node to allow the otherNG-RAN node to control downlink user data flow via the NG-RAN node forthe data radio bearer, the feedback comprising a downlink Data DeliveryStatus (DDDS) frame that comprises: a highest delivered PDCP SequenceNumber (SN) indicator parameter indicating a presence in the DDDS frameof a SN of a highest successfully delivered DL NR PDCP PDU, of the DL NRPDCP PDUs, that is successfully delivered to the UE, and a highestsuccessfully delivered PDCP SN parameter that provides the SN of thehighest successfully delivered DL NR PDCP PDU, the highest successfullydelivered PDCP SN parameter containing 0 when the highest delivered PDCPSN indicator parameter that indicates that the highest successfullydelivered PDCP SN is not present and containing a non-zero number whenthe highest delivered PDCP SN indicator parameter that indicates thatthe highest successfully delivered PDCP SN is present; and a memoryarranged to store the DL NR PDCP PDUs prior to transmission to the UE.

In Example 13, the subject matter of Example 12 includes, wherein: theDDDS frame further comprises a PDU type parameter that indicates a typeof the DDDS frame, a final frame indicator parameter that indicateswhether the DDDS frame is a final DL status report before release of abearer corresponding to the DDDS frame, a highest PDCP transmittedindicator parameter that indicates a presence in the DDDS frame of a SNof a highest transmitted DL NR PDCP PDU, of the DL NR PDCP PDUs, that istransmitted to the UE, and a lost packet report parameter that indicateswhether a number of lost SN ranges reported and a start and end of alost SN range is present in the DDDS frame, and the highest deliveredPDCP SN indicator parameter, the highest transmitted PDCP SN parameter,the PDU type parameter, the final frame indicator parameter and the lostpacket report parameter are provided in a first octet of the DDDS frame.

In Example 14, the subject matter of Example 13 includes, wherein thehighest delivered PDCP SN indicator parameter, the highest transmittedPDCP SN parameter, the final frame indicator parameter and the lostpacket report parameter are each a single bit and the PDU type parameteris multiple bits.

In Example 15, the subject matter of Examples 12-14 includes, by theNG-RAN node, the spare field reserved for later versions of DDDS frames.

In Example 16, the subject matter of Examples 12-15 includes, whereinthe DDDS frame further comprises: a highest transmitted PDCP SN fieldthat provides feedback about a transmitted status of the PDCP PDUsequence to lower layers at the NG-RAN node, a desired buffer size for aradio data bearer corresponding to the DDDS frame, a number of lost SNranges, and a start and end of a lost SN range reported in the DDDSframe to be lost.

In Example 17, the subject matter of Example 16 includes, wherein: thedesired buffer size occurs in the DDDS frame after a first octet, thenumber of lost SN ranges occurs in the DDDS frame after the desiredbuffer size, and the start and end of a lost SN range occurs in the DDDSframe after the number of lost SN ranges.

In Example 18, the subject matter of Examples 16-17 includes, wherein:the desired buffer size is 4 octets, the number of lost SN ranges is asingle octet, and the start and end of a lost SN range are up to 6octets.

Example 19 is a non-transitory computer-readable storage medium thatstores instructions for execution by one or more processors of a nextgeneration radio access network (NG-RAN) node, the one or moreprocessors to configure the NG-RAN node to, when the instructions areexecuted: transmit, to another NG-RAN node over an Xn-User plane (Xn-U)interface, downlink (DL) new radio (NR) packet data convergence protocol(PDCP) packet data units (PDUs) for a user equipment (UE) fortransmission by the other NG-RAN to the UE on a data radio bearer;receive feedback from the other NG-RAN node to allow the NG-RAN node tocontrol downlink user data flow for the data radio bearer, the feedbackcomprising a downlink Data Delivery Status (DDDS) frame that comprises:a highest delivered PDCP Sequence Number (SN) indicator parameterindicating a presence in the DDDS frame of a SN of a highestsuccessfully delivered DL NR PDCP PDU, of the DL NR PDCP PDUs, that issuccessfully delivered to the UE, and a highest successfully deliveredPDCP SN parameter that provides the SN of the highest successfullydelivered DL NR PDCP PDU, the highest successfully delivered PDCP SNparameter containing 0 when the highest delivered PDCP SN indicatorparameter that indicates that the highest successfully delivered PDCP SNis not present and containing a non-zero number when the highestdelivered PDCP SN indicator parameter that indicates that the highestsuccessfully delivered PDCP SN is present; and remove buffered DL NRPDCP PDUs of DL NR PDCP PDUs reported by the DDDS message as at leastone of transmitted or successfully delivered DL NR PDCP PDUs.

In Example 20, the subject matter of Example 19 includes, wherein: theDDDS frame further comprises a PDU type parameter that indicates a typeof the DDDS frame, a final frame indicator parameter that indicateswhether the DDDS frame is a final DL status report before release of abearer corresponding to the DDDS frame, a highest PDCP transmittedindicator parameter that indicates a presence in the DDDS frame of a SNof a highest transmitted DL NR PDCP PDU, of the DL NR PDCP PDUs, that istransmitted to the UE, and a lost packet report parameter that indicateswhether a number of lost SN ranges reported and a start and end of alost SN range is present in the DDDS frame, the highest delivered PDCPSN indicator parameter, the highest transmitted PDCP SN parameter, thePDU type parameter, the final frame indicator parameter and the lostpacket report parameter are provided in a first octet of the DDDS frame,and the highest delivered PDCP SN indicator parameter, the highesttransmitted PDCP SN parameter, the final frame indicator parameter andthe lost packet report parameter are each a single bit and the PDU typeparameter is multiple bits.

Example 21 is at least one machine-readable medium includinginstructions that, when executed by processing circuitry, cause theprocessing circuitry to perform operations to implement of any ofExamples 1-20.

Example 22 is an apparatus comprising means to implement of any ofExamples 1-20.

Example 23 is a system to implement of any of Examples 1-20.

Example 24 is a method to implement of any of Examples 1-20.

Although an embodiment has been described with reference to specificexample embodiments, it will be evident that various modifications andchanges may be made to these embodiments without departing from thebroader scope of the present disclosure. Accordingly, the specificationand drawings are to be regarded in an illustrative rather than arestrictive sense. The accompanying drawings that form a part hereofshow, by way of illustration, and not of limitation, specificembodiments in which the subject matter may be practiced. Theembodiments illustrated are described in sufficient detail to enablethose skilled in the art to practice the teachings disclosed herein.Other embodiments may be utilized and derived therefrom, such thatstructural and logical substitutions and changes may be made withoutdeparting from the scope of this disclosure. This Detailed Description,therefore, is not to be taken in a limiting sense, and the scope ofvarious embodiments is defined only by the appended claims, along withthe full range of equivalents to which such claims are entitled.

The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin a single embodiment for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed embodiments require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus, the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separate embodiment.

What is claimed is:
 1. An apparatus of a first base station, theapparatus comprising: a memory; and processing circuitry arranged to:determine that downlink (DL) packet data convergence protocol (PDCP)packet data units (PDUs) for a user equipment (UE) are to be transmittedto a second base station for transmission to the UE; generate, fortransmission to the second base station over an interface, the DL PDCPPDUs for transmission to the UE; extract from a downlink Data DeliveryStatus (DDDS) frame received from the second base station: a highestdelivered PDCP Sequence Number (SN) indicator parameter indicating apresence in the DDDS frame of a SN of a highest successfully deliveredDL PDCP PDU, of the DL NR PDCP PDUs, that is successfully delivered tothe UE; and a highest successfully delivered PDCP SN parameter thatprovides the SN of the highest successfully delivered DL PDCP PDU, whenindicated to be present by the highest successfully delivered PDCP SNindicator parameter; and instruct the memory to remove a set of storedDL PDCP PDUs of DL PDCP PDUs indicated by the DDDS frame as at least oneof transmitted or successfully delivered DL PDCP PDUs.
 2. The apparatusof claim 1, wherein the DDDS frame is usable for both X2 interface DDDSmessages and Xn-interface DDDS messages.
 3. The apparatus of claim 1,wherein the interface comprises one of: an Xn-User plane (Xn-U)interface; or an X2-User plane (X2-U) interface.
 4. The apparatus ofclaim 1, wherein successfully delivered DL PDCP PDUs comprise DL PDCPPDUs that are delivered in-sequence.
 5. The apparatus of claim 1,wherein: the DDDS frame further comprises a PDU type parameter thatindicates a type of the DDDS frame, a final frame indicator parameterthat indicates whether the DDDS frame is a final DL status report beforerelease of a bearer corresponding to the DDDS frame, a highest PDCPtransmitted indicator parameter that indicates a presence in the DDDSframe of a SN of a highest transmitted DL PDCP PDU, of the DL PDCP PDUs,that is transmitted to the UE, and a lost packet report parameter thatindicates whether a number of lost SN ranges reported and a start andend of a lost SN range is present in the DDDS frame, and the highestdelivered PDCP SN indicator parameter, the highest transmitted PDCP SNparameter, the PDU type parameter, the final frame indicator parameterand the lost packet report parameter are provided in a first octet ofthe DDDS frame.
 6. The apparatus of claim 5, wherein the highestdelivered PDCP SN indicator parameter, the highest transmitted PDCP SNparameter, the final frame indicator parameter and the lost packetreport parameter are each a single bit and the PDU type parameter ismultiple bits.
 7. An apparatus of a second base station, the apparatuscomprising: processing circuitry arranged to: encode, for transmissionto a user equipment (UE) on a radio bearer, downlink (DL) packet dataconvergence protocol (PDCP) packet data units (PDUs) from a first basestation over an interface; determine transmission characteristics of theDL PDCP PDUs; and generate feedback for transmission to the first basestation to allow the first base station to control downlink user dataflow via the second base station for the data radio bearer, the feedbackcomprising a downlink Data Delivery Status (DDDS) frame that comprises:a highest delivered PDCP Sequence Number (SN) indicator parameterindicating a presence in the DDDS frame of a SN of a highestsuccessfully delivered DL PDCP PDU, of the DL PDCP PDUs, that issuccessfully delivered to the UE, and a highest successfully deliveredPDCP SN parameter that provides the SN of the highest successfullydelivered DL PDCP PDU, when indicated to be present by the highestsuccessfully delivered PDCP SN indicator parameter; and a memoryarranged to store the DL PDCP PDUs prior to transmission to the UE. 8.The apparatus of claim 7, wherein the DDDS frame is usable for both X2interface DDDS messages and Xn-interface DDDS messages.
 9. The apparatusof claim 7, wherein the interface comprises one of: an Xn-User plane(Xn-U) interface; or an X2-User plane (X2-U) interface.
 10. Theapparatus of claim 7, wherein successfully delivered DL PDCP PDUscomprise DL PDCP PDUs that are delivered in-sequence.
 11. The apparatusof claim 7, wherein: the DDDS frame further comprises a PDU typeparameter that indicates a type of the DDDS frame, a final frameindicator parameter that indicates whether the DDDS frame is a final DLstatus report before release of a bearer corresponding to the DDDSframe, a highest PDCP transmitted indicator parameter that indicates apresence in the DDDS frame of a SN of a highest transmitted DL PDCP PDU,of the DL PDCP PDUs, that is transmitted to the UE, and a lost packetreport parameter that indicates whether a number of lost SN rangesreported and a start and end of a lost SN range is present in the DDDSframe, and the highest delivered PDCP SN indicator parameter, thehighest transmitted PDCP SN parameter, the PDU type parameter, the finalframe indicator parameter and the lost packet report parameter areprovided in a first octet of the DDDS frame.
 12. The apparatus of claim7, wherein the highest delivered PDCP SN indicator parameter, thehighest transmitted PDCP SN parameter, the final frame indicatorparameter and the lost packet report parameter are each a single bit andthe PDU type parameter is multiple bits.
 13. The apparatus of claim 7,wherein the DDDS frame further comprises: a highest transmitted PDCP SNfield that provides feedback about a transmitted status of the PDCP PDUsequence to lower layers at the second base station, a desired buffersize for a radio data bearer corresponding to the DDDS frame, a numberof lost SN ranges, and a start and end of a lost SN range reported inthe DDDS frame to be lost.
 14. The apparatus of claim 13, wherein: thedesired buffer size occurs in the DDDS frame after a first octet, thenumber of lost SN ranges occurs in the DDDS frame after the desiredbuffer size, and the start and end of a lost SN range occurs in the DDDSframe after the number of lost SN ranges.
 15. The apparatus of claim 13,wherein: the desired buffer size is 4 octets, the number of lost SNranges is a single octet, and the start and end of a lost SN range areup to 6 octets.
 16. A non-transitory computer-readable storage mediumthat stores instructions for execution by one or more processors of asecond base station, wherein the one or more processors are configuredto execute the instructions to cause the second base station to: encode,for transmission to a user equipment (UE) on a radio bearer, downlink(DL) packet data convergence protocol (PDCP) packet data units (PDUs)from a first base station over an interface; determine transmissioncharacteristics of the DL PDCP PDUs; and generate feedback fortransmission to the first base station to allow the first base stationto control downlink user data flow via the second base station for thedata radio bearer, the feedback comprising a downlink Data DeliveryStatus (DDDS) frame that comprises: a highest delivered PDCP SequenceNumber (SN) indicator parameter indicating a presence in the DDDS frameof a SN of a highest successfully delivered DL PDCP PDU, of the DL PDCPPDUs, that is successfully delivered to the UE, and a highestsuccessfully delivered PDCP SN parameter that provides the SN of thehighest successfully delivered DL PDCP PDU, when indicated to be presentby the highest successfully delivered PDCP SN indicator parameter; and amemory arranged to store the DL PDCP PDUs prior to transmission to theUE.
 17. The non-transitory computer-readable storage medium of claim 16,wherein the DDDS frame is usable for both X2 interface DDDS messages andXn-interface DDDS messages.
 18. The non-transitory computer-readablestorage medium of claim 16, wherein the interface comprises one of: anXn-User plane (Xn-U) interface; or an X2-User plane (X2-U) interface.19. The non-transitory computer-readable storage medium of claim 16,wherein successfully delivered DL PDCP PDUs comprise DL PDCP PDUs thatare delivered in-sequence.
 20. The non-transitory computer-readablestorage medium of claim 16, wherein: the DDDS frame further comprises aPDU type parameter that indicates a type of the DDDS frame, a finalframe indicator parameter that indicates whether the DDDS frame is afinal DL status report before release of a bearer corresponding to theDDDS frame, a highest PDCP transmitted indicator parameter thatindicates a presence in the DDDS frame of a SN of a highest transmittedDL PDCP PDU, of the DL PDCP PDUs, that is transmitted to the UE, and alost packet report parameter that indicates whether a number of lost SNranges reported and a start and end of a lost SN range is present in theDDDS frame, the highest delivered PDCP SN indicator parameter, thehighest transmitted PDCP SN parameter, the PDU type parameter, the finalframe indicator parameter and the lost packet report parameter areprovided in a first octet of the DDDS frame, and the highest deliveredPDCP SN indicator parameter, the highest transmitted PDCP SN parameter,the final frame indicator parameter and the lost packet report parameterare each a single bit and the PDU type parameter is multiple bits.